\begin{table}[htbp]\centering
\small
\def\sym#1{\ifmmode^{#1}\else\(^{#1}\)\fi}
\caption{Monthly IRRs of Loan Portfolios \label{tab:r_treatment_irr}}
\begin{tabular}{l*{5}{c}}
\toprule
Treatment Group  & \multicolumn{3}{c}{\begin{tabular}{@{}c@{}}\underline{Account percent locked} \\ \end{tabular}} & \begin{tabular}{@{}c@{}}All \\ \end{tabular} & $n$ \\
& 1st tercile & 2nd tercile & 3rd tercile & & \\\addlinespace
& (1) & (2) & (3) & (4) \\
\midrule
Secured & 0.2\% & -2.5\% & -8.4\% & -3.7\%  & 217 \\
&(1.7)&(2.8)&(2.0)&(1.8)\\ 
& [0.00, 0.06] & [0.06, 0.19] & [0.19, 0.57] & [0.00, 0.57]  & \\ \addlinespace 
Unsecured & -3.7  & -6.3 & -10.2 & -6.9 & 438 \\
&(1.4)&(1.1)&(1.3)&(0.8)\\ 
& [0.00, 0.05] & [0.05, 0.19] & [0.19, 0.64] & [0.00, 0.64]  & \\ \addlinespace 
p-value & & & &0.000& \\ \addlinespace 
\midrule
Prior School-Fee & 6.6  & 6.0 & 3.2 & 5.1  & 1377 \\
Loans (Secured) &(0.4)&(0.6)&(0.4)&(0.2)\\ 
& [0.00, 0.04] & [0.04, 0.13] & [0.13, 0.30] & [0.00, 0.30]  & \\ 
\addlinespace\bottomrule
\end{tabular}
\end{table}
